Refactor server init to use template files with --template flag

Restructures the `docker mcp server init` command to use file-based templates
instead of embedded constants, making it easier to maintain and extend.

Changes:
- Created two template directories:
  - templates/basic: Simple MCP server without UI
  - templates/chatgpt-app-basic: MCP server with ChatGPT App UI
- Each template has separate .tmpl files for all generated files
- Refactored init.go to use go:embed and text/template
- Added required --template flag to init command
- Template files use {{.ServerName}} for customization

Templates:
- basic: Simple greeter with single name parameter, no UI
- chatgpt-app-basic: Greeter with dropdown (Hi/Hey/Hello), UI resource,
  and full ChatGPT App integration

Usage:
- docker mcp server init --template=basic my-server
- docker mcp server init --template=chatgpt-app-basic my-app

Benefits:
- Easy to add new templates (just create new folder)
- Templates are actual files, easier to edit and test
- Clear separation between basic and ChatGPT App templates
- Better error messages for invalid templates

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: kgprs

cmd/docker-mcp/commands/server.go

@@ -119,18 +119,19 @@ func serverCommand(docker docker.Client, dockerCli command.Cli) *cobra.Command {
 	})
 
 	var language string
+	var templateName string
 	initCommand := &cobra.Command{
 		Use:   "init <directory>",
 		Short: "Initialize a new MCP server project",
 		Long:  "Initialize a new MCP server project in the specified directory with boilerplate code, Dockerfile, and compose.yaml",
 		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			dir := args[0]
-			if err := server.Init(cmd.Context(), dir, language); err != nil {
+			if err := server.Init(cmd.Context(), dir, language, templateName); err != nil {
 				return err
 			}
 			serverName := filepath.Base(dir)
-			fmt.Fprintf(cmd.OutOrStdout(), "Successfully initialized MCP server project in %s\n", dir)
+			fmt.Fprintf(cmd.OutOrStdout(), "Successfully initialized MCP server project in %s (template: %s)\n", dir, templateName)
 			fmt.Fprintf(cmd.OutOrStdout(), "Next steps:\n")
 			fmt.Fprintf(cmd.OutOrStdout(), "  cd %s\n", dir)
 			fmt.Fprintf(cmd.OutOrStdout(), "  docker build -t %s:latest .\n", serverName)
@@ -139,6 +140,8 @@ func serverCommand(docker docker.Client, dockerCli command.Cli) *cobra.Command {
 		},
 	}
 	initCommand.Flags().StringVar(&language, "language", "go", "Programming language for the server (currently only 'go' is supported)")
+	initCommand.Flags().StringVar(&templateName, "template", "basic", "Template to use (basic, chatgpt-app-basic)")
+	initCommand.MarkFlagRequired("template")
 	cmd.AddCommand(initCommand)
 
 	return cmd